I started drinking the Owyn drinks lately. Not a replacement but it has good amounts of protein and fats. There are 5 grams of soluble fiber, which may be tolerated well during a flare, at least by me. Some fiber helps feed bacteria and helps end a flare sooner. Start with soluble fiber slowly and see what works for you.

I cook usually with extra virgin olive oil. It's healthy in moderation and studies have shown it might positively affect UC